1. Field of the Invention
The invention relates to a system and a method for controlling and monitoring an aircraft, and more particularly a system for controlling the temperature of air taps and for monitoring the exceeding of a predefined temperature threshold in an aircraft.
2. Description of the Related Art
A known aircraft such as, for example, an airplane, comprises a fuselage containing a cockpit deck and a passenger cabin and at least one engine set. Such an engine set comprises an engine and a fan from which air tappings can be made. Such tappings are made by a system, called air tapping system, comprising a plurality of valves and a precooler. These valves make it possible to tap air in various air flows circulating in or around the engine, for example a flow of air at high pressure, at high temperature, tapped on the engine, a flow of air at intermediate pressure, at lower temperature, also tapped on the engine and a fan air flow, cold, tapped on the fan. The flow of air at high pressure and the flow of air at intermediate pressure can be mixed into a mixed flow supplied to the precooler. The precooler then allows for heat exchange between the mixed flow and the fan air flow making it possible to lower the temperature of the mixed flow at the precooler outlet so as to supply, for example to the cockpit or to the passenger cabin of the aircraft, a flow with a regulated temperature.
Such regulation is obtained by controlling the opening of one or more of the air flow tapping valves. The temperature of the air flow can be regulated by the selection of one or more valves to be controlled, for example, by controlling the opening or the closing of the fan air flow tapping valve.
A system is known in which, on the one hand, a control of the temperature is made in order to allow for the opening or the closing of one or more valves and, on the other hand, a monitoring of the exceeding of a predefined temperature threshold is performed in order to allow for the closure of one or more valves, for example hot air tapping valves, or the opening of one or more valves, for example cold air tapping valves, in case said threshold is exceeded. Such exceeding occurs, for example, when the temperature of tapped air intended for the cockpit is too high, this type of incident being classified as catastrophic in terms of aircraft safety.
A known air tapping system comprises a thermostat, connected directly to one or more valves and making it possible to control the temperature of air tappings on said valve or valves, the opening of the valve or valves being modulated by the thermostat signal. Such a thermostat does, however, induce inaccuracies in the temperature measurements and therefore, by extension, in their control.
One existing solution consists in placing a temperature sensor to measure the temperature of the flow coming from the precooler and report this measurement to an air tapping system management computer, dedicated to the air tapping system. The duly obtained measurement then enables the computer to perform both the control of the air tapping temperature and the monitoring of the exceeding of a predefined temperature threshold by the temperature of the air tapping. The use of such a measurement does, however, induce a common mode problem. In practice, since the control and monitoring depend, in such a case, simultaneously on the same temperature measurement, an incorrect measurement implies both a poor control of the air tapping temperature and a poor monitoring of the exceeding of a predefined air tapping temperature threshold, which presents a problem in terms of aircraft safety.